1. Field of the Invention
The present invention relates to a micro device and a method of manufacturing the same. More particularly, the invention relates to a method of manufacturing an ink-jet printing head wherein a part of a pressure generating chamber communicating with a nozzle aperture for ejecting ink droplets is composed of a diaphragm, a piezoelectric element is provided via the diaphragm and an ink droplet is ejected by the displacement of the piezoelectric element, the ink-jet printing head so manufactured and an ink-jet printing device including such an ink-jet printing head.
2. Related Art
Heretofore, there is an ink-jet printing head as one type of a micro device provided with an active plate and an active plate actuator for driving the active plate on one side of a substrate.
There has been known two different types of such an ink-jet printing head in which a part of a pressure generating chamber communicating with a nozzle aperture for ejecting ink droplets is composed of a diaphragm, an ink droplet is ejected from a nozzle aperture by deforming the diaphragm by a piezoelectric element and pressurizing ink in the pressure generating chamber. One type employs a piezoelectric actuator in a longitudinal vibration mode in which the piezoelectric element expands and contracts in an axial direction, whereas the other type includes a piezoelectric actuator in a flexural vibration mode.
For the former type, the volume of a pressure generating chamber can vary by contacting an end face of the piezoelectric element to a diaphragm and a head suitable for high density printing can be manufactured. However, this type requires a difficult process for cutting into piezoelectric elements according to the arrangement pitch of nozzle apertures like the teeth of a comb and work for positioning and fixing the cut piezoelectric element on a pressure generating chamber. Thus, this type of the printing head requires a complicated manufacturing process.
In the meantime, for the latter type, a piezoelectric element can be attached onto a diaphragm in a relatively simple process for sticking and burning a green sheet serving as a piezoelectric material so that the shape is in the shape of a pressure generating chamber. However, a certain area is required because flexural vibration is utilized and, hence, it is difficult to form a high density arrangement.
To solve the problems of the printing head equivalent to the latter type, a printing head wherein a uniform piezoelectric material layer is formed overall on the surface of a diaphragm using film forming technique, the piezoelectric material layer is cut into a shape corresponding to a pressure generating chamber by lithography and a piezoelectric element is independently formed for every pressure generating chamber is proposed as disclosed in Unexamined Japanese Patent Publication No. Hei. 5-286131.
Hereby, there are advantages for not demanding work for sticking a piezoelectric element on a diaphragm and a piezoelectric element can be fixed by a precise, simple method of lithography. In addition, a piezoelectric element can be thinned that enables high speed driving.
In this case, a monocrystalline silicon substrate, for example, can be used for a substrate, a pressure generating chamber and a passage such as a reservoir can be formed by anisotropic etching and recording density can be enhanced by reducing the area of the opening of a pressure generating chamber as much as possible.
When the above monocrystalline silicon substrate is anisotropically etched, parts to be through holes such as a reference hole for positioning, an ink inlet and a separating hole are formed simultaneously with pressure generating chambers. At this time, generally, after the monocrystalline silicon substrate, except a silicon dioxide film which is the lower layer, is etched, a part of a film corresponding to a through hole is etched or removed physically. However, there is a problem that when the films are removed, surroundings of the through hole are overetched or films around the through hole are peeled. If only the silicone dioxide film is left, there is a problem that etching gas or etchant invades on the reverse side due to the defect of the film. Further, particularly if a part of the films corresponding to a through hole are physically removed by inserting a reference pin and others, there is a problem that a film is freed, invades between the reference pin and the through hole and the failure of alignment is caused.
Such problems are caused not only in an ink-jet printing head but in a micro device such as a micro sensor provided with an active plate and an active plate actuator on one side of a substrate.
In view of the difficulties and problems accompanying the conventional ink-jet printing head, it is an object of the present invention to provide a method of manufacturing a micro device in which a through part can be efficiently and securely formed and such a micro device, particularly a method of manufacturing an ink-jet printing head, such an ink-jet printing head and an ink-jet recording device including such an ink-jet printing head.
A first aspect of the present invention to solve the above problems relates to a micro device based upon a micro device provided with multilayer structure constituting an active plate for performing predetermined action and an active plate actuator for driving the active plate on one side of a substrate and characterized in that a through hole which pierces the above substrate and a fragile part provided around or across a part corresponding to a through hole of a multilayer film and relatively thinner than the other part are provided.
According to such a first aspect, the above multilayer film can be readily cut via the fragile part, the above through hole can be simply formed, a thin film is prevented from being scattered when the through hole is formed, and a reference pin and others can be securely fitted to the through hole.
A second aspect of the present invention relates to a micro device based upon the first embodiment and characterized in that the above multilayer film covering the above part corresponding to a through hole is provided with a film provided with tensile in-plane stress at least on the upper layer and the in-plane stress of the whole multilayer film is directed in the direction of a tensile load, and the above fragile part is provided around or across the part corresponding to a through hole of the multilayer film and includes a fragile cut part relatively lower in fragility than the other part.
According to such a second aspect, when the through hole is formed, the multilayer film is lifted along the edge, and the reference pin and the through hole can be securely touched.
A third aspect of the present invention relates to a micro device based upon the second aspect and characterized in that the above fragile cut part is linearly formed.
According to such a third aspect, the multilayer film is readily cut linearly and a through hole can be further simply formed inside a passage forming substrate.
A fourth aspect of the present invention relates to a micro device based upon the second or third aspect and characterized in that the above fragile cut part is a notched groove formed at least on one layer of the above multilayer film.
According to such a fourth aspect, the multilayer film is readily cut along the notched groove and a through hole can be simply formed inside a passage forming substrate.
A fifth aspect of the present invention relates to a micro device based upon any of the second to fourth aspects and characterized in that the above multilayer film includes a silicon oxide film provided with compressive stress and a metallic film formed on the silicon oxide film and provided with tensile stress.
According to such a fifth aspect, tensile stress is caused by the stress of the silicon oxide film and the stress of the metallic film as a whole in the multilayer film and a through hole can be simply inside a passage forming substrate.
A sixth aspect of the present invention relates to a micro device based upon the fifth aspect and characterized in that the above multilayer film further includes an insulating layer provided with tensile stress as the uppermost layer.
According to such a sixth aspect, the tensile stress of the whole multilayer film is enhanced and when a through hole is formed, the multilayer film is securely lifted and the through hole can be further simply formed inside a passage forming substrate.
A seventh aspect of the present invention relates to a micro device based upon the fifth or sixth aspect and characterized in that the above fragile cut part is a notched groove formed at least in a part at least with the thickness of the metallic film of the above multilayer film.
According to such a seventh aspect, the multilayer film is readily cut by the notched groove of the metallic film and a through hole can be further simply formed inside a passage forming substrate.
An eighth aspect of the present invention relates to a micro device based upon any of the first to sixth aspects and characterized in that the above fragile part includes the above part corresponding to a through hole and includes a linear thin film part thinner as a whole than the surroundings of the above multilayer film.
According to such an eighth aspect, the multilayer film can be prevented from being peeled outside the thin film part.
A ninth aspect of the present invention relates to a micro device based upon the eighth aspect and characterized in that a thick film part relatively thicker than the above thin film part is further provided inside the thin film part.
According to such a ninth aspect, the thick film part left when a cap covering a through hole is removed exists inside the thin film part.
A tenth aspect of the present invention relates to an ink-jet printing head based upon any of the first to ninth aspects and characterized in that the above substrate is provided with a row of pressure generating chambers each of which communicates with a nozzle aperture on the other side of the substrate and is partitioned by plural partition walls, and the above substrate is a passage forming substrate provided on one side of the substrate with a piezoelectric element at least including a lower electrode, a piezoelectric layer and an upper electrode layer and formed in an area opposite to the above pressure generating chamber via an elastic film constituting a part of the pressure generating chamber.
According to such a tenth aspect, an ink-jet printing head wherein a through hole can be simply formed inside a passage forming substrate is realized.
An eleventh aspect of the present invention relates to an ink-jet printing head based upon the tenth aspect and characterized in that the above thin film part is composed of at least an elastic film and the above thick film part is composed of at least one of the above elastic film, the above lower electrode, the above piezoelectric layer and the above upper electrode.
According to such an eleventh aspect, when a part in which a film is removed around a through hole is formed, effect upon the thick film part is avoided by the thin film part composed of an elastic film.
A twelfth aspect of the present invention relates to an ink-jet printing head based upon the eleventh aspect and characterized in that at least a part in the direction of the thickness of the above elastic film of the above thin film part is removed.
According to such a twelfth aspect, when a part in which a film is removed is formed around a through hole, effect upon the thick film part is avoided by a thin elastic film or the above part in which an elastic film is completely removed.
A thirteenth aspect of the present invention relates to an ink-jet recording device characterized in that the above recording device is provided with the ink-jet printing head according to any of the tenth to twelfth aspects.
According to such a thirteenth aspect, the head can be securely and simply manufactured and the ink-jet recording device is readily manufactured.
A fourteenth aspect of the present invention relates to a method of manufacturing a micro device based upon a method of manufacturing a micro device provided with multilayer structure constituting an active plate for performing predetermined action and an active plate actuator for driving the active plate on one side of a substrate and characterized in that a step forming a fragile part relatively thinner than the other part of a multilayer film around or across a part corresponding to a through hole which pierces the substrate in the multilayer film, a step for forming a through part which pierces the multilayer film by etching the part corresponding to a through hole from the other side of the substrate and a step for forming the above through hole along or inside the fragile part by cutting the multilayer film and forming an opening in the multilayer film after the through part is formed are provided.
According to such a fourteenth aspect, the through hole can be simply formed, a thin film is prevented from being scattered when the through part is formed and a reference pin and others can be securely fitted to the through hole.
A fifteenth aspect of the present invention relates to a method of manufacturing a micro device based upon the fourteenth aspect and characterized in that a step for providing a film provided with tensile in-plane stress at least as an upper layer of a multilayer film covering a part corresponding to a through hole which pierces the above substrate so that the in-plane stress of the whole multilayer film is tensile stress is provided before the above through hole is formed, and an opening is formed in the multilayer film utilizing tensile in-plane stress after the through part is formed to form the through hole.
According to such a fifteenth aspect, the multilayer film is lifted along the edge, and a reference pin and the through hole can be securely touched.
A sixteenth aspect of the present invention relates to a method of manufacturing a micro device based upon the fifteenth aspect and characterized in that the above fragile part includes a fragile cut part along the edge of the part corresponding to a through hole of the above multilayer film and relatively lower in fragility than the other part.
According to such a sixteenth aspect, the multilayer film is lifted along the edge when the through hole is formed, and a reference pin and the through hole can be securely touched.
A seventeenth aspect of the present invention relates to a method of manufacturing a micro device based upon the fifteenth or sixteenth aspect and characterized in that the above fragile part is provided across the part corresponding to a through hole of the above multilayer film and includes a fragile cut part relatively lower in fragility than the other part.
According to such a seventeenth aspect, the multilayer film is cut in the center of the through hole, is securely lifted along the edge, and a reference pin and the through hole can be securely touched.
An eighteenth aspect of the present invention relates to a method of manufacturing a micro device based upon the sixteenth or seventeenth aspect and characterized in that the above fragile cut part is formed linearly.
According to such an eighteenth aspect, the multilayer film is cut along the linear fragile part and a through hole can be further simply formed.
A nineteenth aspect of the present invention relates to a method of manufacturing a micro device based upon any of the fifteenth to eighteenth aspects and characterized in that the above fragile cut part is a notched groove formed at least in one layer of the above multilayer film.
According to such a nineteenth aspect, the multilayer film is readily cut along the notched groove and a through hole can be simply formed.
A twentieth aspect of the present invention relates to a method of manufacturing a micro device based upon any of the fifteenth to nineteenth aspects and characterized in that the above multilayer film includes a silicon oxide film provided with compressive stress and a metallic film formed on the silicon oxide film and provided with tensile stress.
According to such a twentieth aspect, tensile stress is caused by the stress of the silicon oxide film and the stress of the metallic film in the multilayer film as a whole and a through hole can be simply formed.
A twenty-first aspect of the present invention relates to a method of manufacturing a micro device based upon the twentieth aspect and characterized in that the above multilayer film is further provided with an insulating layer provided with tensile stress as an upper layer.
According to such a twenty-first aspect, the tensile stress of the whole multilayer film is enhanced, the multilayer film is securely lifted and a through hole can be further simply formed.
A twenty-second aspect of the present invention relates to a method of manufacturing a micro device based upon the twentieth or twenty-first aspect and characterized in that the above fragile cut part is a notched groove formed at least in a part at least with the thickness of the metallic film of the above multilayer film.
According to such a twenty-second aspect, the multilayer film is readily cut with a notched groove composed of a platinum film.
A twenty-third aspect of the present invention relates to a method of manufacturing a micro device based upon any of the fourteenth to twenty-second aspects and characterized in that the above opening is formed by pressing the multilayer film in the above part corresponding to a through hole.
According to such a twenty-third aspect, the multilayer film is lifted along the fragile part by forming the opening by pressing and a through hole in a predetermined shape can be obtained.
A twenty-fourth aspect of the present invention relates to a method of manufacturing a micro device based upon the twenty-third aspect and characterized in that the multilayer film is pressed from the side of the above through part.
According to such a twenty-fourth aspect, the multilayer film is lifted outside the through hole by pressing the multilayer film from the side of the through part and a through hole can be securely formed.
A twenty-fifth aspect of the present invention relates to a method of manufacturing a micro device based upon the twenty-third or second aspect and characterized in that a crack is made at least in a part of the above fragile cut part before pressing.
According to such a twenty-fifth aspect, as a result of making the crack in a part of the fragile part, a through hole can be readily formed.
A twenty-sixth aspect of the present invention relates to a method of manufacturing a micro device based upon any of the fourteenth to twenty-fifth aspects and characterized in that the above fragile part surrounds the above part corresponding to a through hole and includes a linear thin film part thinner as a whole than the surroundings of the above multilayer film.
According to such a twenty-sixth aspect, the multilayer film outside the thin film part is never peeled.
A twenty-seventh aspect of the present invention relates to a method of manufacturing a micro device based upon the twenty-sixth aspect and characterized in that a step for forming the above fragile part includes a step for forming the above thin film part and a cap thicker as a whole than the thin film part and covering the above part corresponding to a through hole and after the through part is formed, the through hole is formed by removing the above cap.
According to such a twenty-seventh aspect, the above cap prevents etchant from leaking in etching a through hole and as the thin film part exists around the through hole-when the cap is removed after etching, the cap can be simply and securely removed.
A twenty-eighth aspect of the present invention relates to a method of manufacturing a micro device based upon the twenty-seventh aspect and characterized in that at least the edge of the above thin film part surrounds the part corresponding to a through hole.
According to such a twenty-eighth aspect, as at least the edge of the thin film part surrounds the part corresponding to a through hole, the inner edge of the thin film part may be also located in a position opposite to the through hole.
A twenty-ninth aspect of the present invention relates to a method of manufacturing a micro device based upon the twenty-seventh or twenty-eighth aspect and characterized in that the above cap is physically removed, attracting it.
According to such a twenty-ninth aspect, when the cap is physically removed after etching, dust and others are removed by attraction.
A thirtieth aspect of the present invention relates to a method of manufacturing a micro device based upon any of the twenty-seventh to twenty-ninth aspects and characterized in that the above cap is removed by mechanical working or working by a laser beam.
According to such a thirtieth aspect, the cap is simply removed using a needle and others or by radiating a laser beam after etching and at that time, a bad effect upon films around the thin film part is prevented by the thin film part.
A thirty-first aspect of the present invention relates to a method of manufacturing a micro device based upon any of the twenty-eighth to thirtieth aspects and characterized in that the above cap is removed by etching.
According to such a thirty-first aspect, the cap is securely removed by etching after etching and at that time, effect upon the surrounding films by overetching is prevented by the thin film part.
A thirty-second aspect of the present invention relates to a method of manufacturing a micro device based upon any of the fourteenth to thirty-first aspects and characterized in that the above substrate is a monocrystalline silicon substrate and the above multilayer structure is formed by forming films and lithography.
According to such a thirty-second aspect, a through hole can be formed by anisotropically etching the monocrystalline silicon substrate, and etching, work for forming an opening and others at that time can be simply and securely performed.
A thirty-third aspect of the present invention relates to a method of manufacturing an ink-jet printing head based upon any of the fourteenth to thirty-second aspects and characterized in that a nozzle aperture is formed on the other side of the above substrate, is provided with a row of pressure generating chambers each of which is partitioned by plural partition walls and is a passage forming substrate provided on one side with a piezoelectric element at least including a lower electrode, a piezoelectric layer and an upper electrode in an area opposite to each pressure generating chamber via an elastic film constituting a part of the pressure generating chamber.
According to such a thirty-third aspect, a through hole such as a reference hole formed in the passage forming substrate of the ink-jet printing head can be securely and simply formed.
A thirty-fourth aspect of the present invention relates to a method of manufacturing an ink-jet printing head based upon the thirty-third aspect and characterized in that the above cap is composed of at least one of the above elastic film, the above lower electrode, the above piezoelectric layer and the above upper electrode and the above thin film part is composed of at least the elastic film.
According to such a thirty-fourth aspect, leakage in etching is securely prevented by the elastic film and the other films and work for an opening can be simply and securely performed.
A thirty-fifth aspect of the present invention relates to as method of manufacturing an ink-jet printing head based upon the thirty-third aspect and characterized in that the above cap is composed of the above elastic film and the above thin film part is composed an elastic film or a film removed part relatively thinner than the above elastic film.
According to such a thirty-fifth aspect, as the thin film part is very thin or there is no thin film part, the film can be very simply and securely removed after etching.